diff options
| author | Alan Cox <alan@redhat.com> | 2007-07-15 23:39:43 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-07-16 09:05:41 -0700 |
| commit | 9c1729db3e6d738f872bcb090212af00473bf666 (patch) | |
| tree | be68b99784607953fb50d9330d34c2728215be57 /drivers/char/n_tty.c | |
| parent | c9c64155f5a81b4b41e98f9fb9c464a565c1bf72 (diff) | |
Prevent an O_NDELAY writer from blocking when a tty write is blocked by the tty atomic writer mutex
Without this a tty write could block if a previous blocking tty write was
in progress on the same tty and blocked by a line discipline or hardware
event. Originally found and reported by Dave Johnson.
Signed-off-by: Alan Cox <alan@redhat.com>
Acked-by: Dave Johnson <djohnson+linux-kernel@sw.starentnetworks.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/char/n_tty.c')
| -rw-r--r-- | drivers/char/n_tty.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/char/n_tty.c b/drivers/char/n_tty.c index 154f42203b05..371631f4bfb9 100644 --- a/drivers/char/n_tty.c +++ b/drivers/char/n_tty.c @@ -1538,7 +1538,8 @@ static unsigned int normal_poll(struct tty_struct * tty, struct file * file, pol else tty->minimum_to_wake = 1; } - if (tty->driver->chars_in_buffer(tty) < WAKEUP_CHARS && + if (!tty_is_writelocked(tty) && + tty->driver->chars_in_buffer(tty) < WAKEUP_CHARS && tty->driver->write_room(tty) > 0) mask |= POLLOUT | POLLWRNORM; return mask; |